Electrically enhanced combustion control system with multiple power sources and method of operation

ABSTRACT

A combustion system is provided that includes a fuel nozzle configured to support a combustion reaction, and an electrode positioned to apply an electrical charge to the combustion reaction. A power converter is positioned to receive heat produced by the combustion reaction and to convert a portion of the received heat to electrical energy. A combustion system controller is configured to provide the electrical charge to the electrode, using energy drawn either from the power converter or from a power storage element, depending on an amount of power being produced by the power converter and on a state-of-charge of the power storage element. The controller is further configured to use surplus energy generated by the power converter to recharge the power storage element.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority benefit from U.S. ProvisionalPatent Application No. 61/822,538, entitled “ELECTRICALLY ENHANCEDCOMBUSTION CONTROL SYSTEM WITH MULTIPLE POWER SOURCES AND METHOD OFOPERATION”, filed May 13, 2013; which, to the extent not inconsistentwith the disclosure herein, is incorporated by reference.

SUMMARY

According to an embodiment, a combustion system is provided thatincludes a fuel nozzle configured to support a combustion reaction, andan electrode positioned to apply an electrical charge to the combustionreaction. A power converter is positioned to receive heat produced bythe combustion reaction and to convert a portion of the received heat toelectrical energy. A combustion system controller is configured toprovide the electrical charge to the electrode, using energy drawneither from the power converter or from a power storage element,depending on an amount of power being produced by the power converterand on a state-of-charge of the power storage element. The controller isfurther configured to use surplus energy generated by the powerconverter to recharge the power storage element.

According to an embodiment, the combustion system controller isconfigured to draw power from an external power source if the powerconverter is not producing sufficient power to provide the electricalcharge to the electrode and the power storage element is depleted.

According to an embodiment, the combustion system controller isconfigured to transmit power to the external power source if the powerconverter is producing more power than is necessary to provide theelectrical charge to the electrode and the power storage element isfully charged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of a combustion system,according to an embodiment.

FIG. 2 is a view of a portion of the combustion system of FIG. 1,showing in more detail, in particular, a power converter of thecombustion system of FIG. 1, according to an embodiment.

FIG. 3 is a diagrammatic representation of a combustion system,according to another embodiment.

FIG. 4 is a flow chart illustrating elements of a method of operation ofa combustion system, according to an embodiment.

FIG. 5 is a flow chart illustrating elements of a method of operation ofa combustion system, according to another embodiment.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. Other embodiments may be used and/or other changesmay be made without departing from the spirit or scope of thedisclosure.

Electrically enhanced combustion systems (EEC), are combustion systemsthat include a structure configured to apply electrical energy to acombustion reaction. Application of electrical energy to a combustionreaction is described in a number of recent patent applications,including the following, all of which are incorporated herein byreference, in their entireties: “SYSTEM AND APPARATUS FOR APPLYING ANELECTRIC FIELD TO A COMBUSTION VOLUME”, U.S. Non-Provisional patentapplication Ser. No. 12/753,047, filed Apr. 1, 2010; “METHOD ANDAPPARATUS FOR ELECTRICAL CONTROL OF HEAT TRANSFER”, U.S. Non-Provisionalpatent application Ser. No. 13/006,344, filed Jan. 13, 2011; and“MULTIPLE FUEL COMBUSTION SYSTEM AND METHOD”, U.S. Non-Provisionalpatent application Ser. No. 13/731,109, filed Dec. 30, 2012.

As explained in detail in the patent applications referenced above,application of electrical energy, such as a charge or electricalpotential to a combustion reaction typically involves generation of ahigh-voltage signal that can reach values of greater than 100 kV, andapplying that signal to the combustion reaction or supporting fuel jetvia an electrode positioned adjacent to, or in contact with thecombustion reaction and/or fuel jet. The signal can be a constant valuesignal, or can vary over time, can include a wide range of waveforms,and can alternate polarity. Depending on the purpose and configurationof a particular system, application of a charge to the combustionreaction can produce a number of significant benefits, again, asoutlined in the referenced applications.

The inventor has recognized a number of concerns that might beassociated with combustion systems that include the application of acharge to a combustion reaction. For example, there is a widelyperceived danger of injury anytime a high-voltage potential is present,even when as in the present case, the very low current involved reducesthe actual danger. Nevertheless, it is desirable to take steps to ensurethat, in case of a malfunction or fault in the electrical circuitry, ahigh-voltage charge cannot be applied to portions of the system that arenormally operated at relatively low voltages, or that are electricallyneutral. Not only does this help protect users from painful andpotentially harmful shocks, but it also helps protect low-voltagecircuits and equipment from damage resulting from exposure tohigh-voltage potentials.

The inventor has also recognized that in some applications, a source ofelectrical power may be unavailable, or require significant expense toaccess.

For example, in a petroleum refinery, thermal energy is used in manyparts of the processes employed to separate specific compounds fromcrude oil, and to generate reactions for forming other compounds. Giventhe size of many refineries, many of the burner systems employed may bein locations that are far removed from available sources of electricity.Additionally, routing power to those locations may be difficult orimpossible to accomplish without running power lines through areas wherethe presence of such power lines is prohibited because of the dangerposed by the potential for generation of electric sparks.

FIG. 1 is a simplified diagrammatic representation of a combustionsystem 100, according to an embodiment. The system 100 includes a burnerassembly 110, a power converter 120, and a system controller 130.

The burner assembly 110 includes a burner nozzle 112 configured to emita fuel jet 114 configured to support a combustion reaction 116. Anelectrode 118 is positioned and configured to apply a charge to thecombustion reaction 116. The power converter 120 is configured toreceive thermal energy from the combustion reaction 116, and to converta portion of the received thermal energy into electrical energy. Anoutput power level sensor that is incorporated into or coupled to thepower converter 120 provides a signal corresponding to the power outputof the device. Elements of the power converter 120, according to anembodiment, will be described below in more detail with reference toFIG. 2.

The system controller 130 includes a combustion control module 132, apower storage module 134, a controller module 136, and a switch module138. The combustion control module 132 includes an input terminal atwhich it receives a low-voltage supply of power, and an output terminalcoupled to the electrode 118 of the burner assembly 110. The combustioncontrol module 132 is configured to convert the low-voltage power at theinput terminal to a high-voltage signal to be applied to the combustionreaction 116. There are a number of known methods for producing ahigh-voltage signal, including, for example, charge pump, boostconverter, and voltage multiplier, any of which can be employed,according to the particular application. The power storage module 134 isconfigured to receive and store electrical energy for later use. Thepower storage module 134 preferably includes at least one storagebattery, and may, according to various embodiments, include a pluralityof storage batteries arranged in series or parallel, or configured to beindependently charged and discharged. Alternatively, the power storagemodule 134 may employ other devices for storing electrical power, suchas, for example, high-efficiency capacitors. A power storage levelsensor that is incorporated into or coupled to the power storage module134 provides a signal corresponding to the amount of available storedenergy—often referred to as the state-of-charge (SOC) of the device. Theswitch module 138 is coupled to the power converter 120, the combustioncontrol module 132, and the power storage module 134 via powertransmission line 144. Additionally, according to an embodiment, theswitch module 138 includes an input terminal coupled to an externalpower supply 150, such as a local or municipal power grid, etc.

In the embodiment of FIG. 1, the switch module 138 includes first andsecond switches 140, 142. The first switch 140 is an SPTT (single-poletriple throw) switch having a common node coupled to the power converter120, a first position switch node coupled to the external power supply150, a second position switch node coupled to the power storage module134, and a center off position. The second switch 142 is an SPTT switchhaving a common node coupled to the combustion control module 132, afirst position switch node coupled to the power converter 120, a secondposition switch node coupled to the external power supply 150 and athird position switch node coupled to the power storage module 134.

The first switch 140 controls transmission of power from the powerconverter 120, to the external power supply 150 (in the first position),the power storage module 134 (in the second position), or neither (inthe center off position). The second switch 142 controls the source fromwhich power for operation of the combustion control module 132 is drawn.While the second switch 142 is in the first position, the combustioncontrol module 132 is powered by the power converter 120; while in thesecond position, by the external power supply 150; and in the thirdposition, by the power storage module 134.

The controller module 136 is configured to receive data signals from theoutput power level sensor of the power converter 120 and the powerstorage level sensor of the power storage module 134 via data inputlines 146, and to provide control signals to the switch module 138 viacontrol lines 148. The controller module 136 is configured to controldistribution of power from the power converter 120, determine the sourceof power for the combustion control module 132, and regulate the chargecondition of the power storage module 134. The control module 136 can beimplemented in any appropriate form, according to the intended use andoperation of the particular application. Examples of various forms thatmay be employed to control monitoring and switching include hardwarecircuits, with logic gates or feedback circuits, etc.; processorsconfigured to execute software-based instructions; and circuitsemploying combinations of hardware, software, firmware, etc. Inoperation, the controller module 136 compares the power output of thepower converter 120 with first and second output thresholds. The firstoutput threshold corresponds to a minimum level of power necessary topower the combustion control module 132, and the second output thresholdcorresponds to a surplus threshold of power. The controller module 136is also configured to compare the SOC of the power storage module 134with first and second storage thresholds. The first storage thresholdcorresponds to a minimum SOC at which the power storage module 134 issufficiently charged to reliably power the combustion control module132, and the second storage threshold corresponds to an SOC at which thepower storage module is nominally fully charged. While the power outputof the power converter 120 is below the first output threshold—such aswhen the burner assembly 110 has been recently ignited and has not yetreached operating temperature—the output power is not reliablysufficient to power the combustion control module 132. Accordingly, thecontroller module 136 controls the first switch 140 to move to its offposition, and, if the SOC of the power storage module 134 is above thefirst storage threshold, the second switch 142 to move to its thirdposition. In this configuration, the combustion control module 132 ispowered by the power storage module 134. If the SOC is below the firststorage threshold, the controller module 136 controls the second switch142 to move to its second position, in which case the combustion controlmodule 132 is powered by the external power supply 150.

While the power output of the power converter 120 is above the firstoutput threshold but below the second threshold, the output power issufficient to power the combustion control module 132, but may notproduce power beyond that required by the combustion control module. Inthis condition, the controller module 136 controls the first switch 140to move to or remain in its off position and the second switch 142 tomove to its first position. In this configuration, the combustioncontrol module 132 is powered by the power converter 120.

Finally, while the power output of the power converter 120 is abovesecond threshold, the output of the power converter 120 is more thansufficient to power the combustion control module 132, so a portion ofthat power can be drawn off as surplus power. Accordingly, thecontroller module 136 controls the second switch 142 to move to orremain in its first position, in which case the combustion controlmodule 132 is powered by the power converter 120. Additionally, if theSOC of the power storage module 134 is below the second storagethreshold, the controller module 136 controls the first switch 142 tomove to its third position, so that a portion of the power from thepower converter 120 is sent to charge the power storage module 134. Onthe other hand, if the SOC of the power storage module 134 is above thesecond storage threshold (indicating that the storage module is fullycharged), the controller module 136 controls the first switch 142 tomove to its third position, so that a portion of the power from thepower converter 120 is sent to the external power supply 150.

Power sent to the external power supply 150 may be used in a number ofdifferent ways, depending, in part, on the particular powerconfiguration, and on the application. For example, if the combustionsystem 100 is a subsystem of an HVAC system, and the external powersupply 150 is a municipal power supply, power from the power converter120 may be used to offset a portion of the power drawn from the externalpower supply 150 by other subsystems, thereby reducing the power costsincurred by the overall system. If, in another example, the combustionsystem 100 is a subsystem of a refinery, and there is no local access toa municipal power grid, the external power supply 150 can includestorage batteries used to power other local systems such as sensorsuites, computers, wireless transmitters, etc. In such a case, powerfrom the power converter 120 may be used to charge those externalstorage batteries.

Of course, in some cases, there will be no external power supply 150.For example, according to an embodiment, the combustion system 100 is asubsystem of an isolated system that has no access to an external powergrid, and for which the power storage module 134 is a unified energysource, configured to provide power for all subsystems. In such anembodiment, the power converter 120 and the power storage module 134 areconfigured to have the capacity to meet the increased power generationand storage requirements. According to another embodiment, it is simplymore economical to draw the minimal energy necessary to power thecombustion control module 132 from the combustion reaction 116 than toprovide the necessary connections and draw power from the local grid.

According to an embodiment, where no external power supply 150 isavailable or required, the first switch 140 is a single pole, doublethrow (SPDT) switch that is movable between the off position and thesecond position switch node coupled to the power storage module 134.According to another embodiment, the power storage module includes firstand second electric batteries, each of which is capable of powering thecombustion control module 132, and which are separately monitored by thecontrol module 136. Additionally, the switch module 138 is configured toseparately couple the first and second batteries to the power converter120 for recharging, as controlled by the control module 136. U.S.Provisional patent application Ser. No. 61/806,357, filed Mar. 28, 2013,entitled “BATTERY-POWERED HIGH-VOLTAGE CONVERTER CIRCUIT WITH ELECTRICALISOLATION AND MECHANISM FOR CHARGING THE BATTERY”, teaches a system thatincludes first and second batteries in an arrangement similar to thatdescribed here, and which is incorporated herein in its entirety.

Many elements that are known or understood in the art but are notnecessary for an understanding of the principles of the invention areomitted from the drawings and description to avoid unnecessarycomplexity and reduce the likelihood of confusion. Such omitted elementsmay include, for example, voltage regulators rectifiers, logic controlof applied charge, etc.

FIG. 2 is a view of a portion of the combustion system of FIG. 1,showing in more detail, in particular, the power converter 120 of FIG.1, according to an embodiment. The power converter 120 is shown coupledto a wall 200 of an enclosure in which the combustion reaction 116occurs, and includes a block 202 of thermally conductive material, suchas, e.g., copper or aluminum, coupled to the wall 200 of the enclosure.A thermoelectric panel 204 is positioned with a first face in thermalcontact with the side of the block 202 opposite the wall 200, and a heatsink 206 coupled to a second face. The block 202 acts to provide arigid, planar surface to which the thermoelectric panel 204 can becoupled, while the heat sink 206 dissipates heat from the thermoelectricpanel 204 in order to cool the second face. Electricity generated by thethermoelectric panel 204 is transmitted to the system controller 130 viapower transmission line 144. A voltage level sensor 208 is configured todetect a voltage level at the output of the thermoelectric panel 204 andto transmit this information to the system controller 130 via datatransmission line 146.

The voltage level sensor 208 can include, for example, a comparatorconfigured to compare a voltage level at an output of the powerconverter 120 with a reference voltage, and to provide a binary signalindicating whether the voltage at the output is above or below thereference voltage.

Thermoelectric devices are well known, and are commonly used to performvarious functions, according to specific thermoelectric principles. Forexample, the Peltier effect refers to a phenomenon that occurs when anelectrical potential is applied across a junction of two differentconductive materials, in which heat is absorbed at one part of thecircuit and released at another. This effect is often employed to coolmicroprocessors within a computer cabinet, by affixing a thermoelectricpanel similar to the thermoelectric panel 204 of FIG. 2 to the outersurface of a microprocessor, and coupling a heat sink 206 to theopposite side of the panel, also as shown in FIG. 2. When a potential ofthe correct polarity is applied to the thermoelectric panel 204, itdraws heat from the side in contact with the microprocessor, andreleases the heat on the side with the heat sink 206, which in turncarries the heat out to radiator fins where it can be dissipated byconvection. According to another thermoelectric principle, if separatejunctions of the circuit are placed at different temperatures, anelectric current is generated, according to the Seebeck effect. Thegreater the temperature differential between the junctions, the strongerthe electrical current.

In the present embodiment, the thermoelectric panel 204 is positioned onthe wall 200 of the enclosure opposite the combustion reaction 116. Thethermoelectric panel 204 is operated as a Seebeck device, to generateelectricity to power the combustion control module 132 using a verysmall portion of the heat produced by the combustion reaction 116.Because Seebeck operation relies on a temperature differential, the heatsink 206 is configured to efficiently dissipate heat, so that the secondface of the thermoelectric panel 204 is cooler than the first face, inthermal contact with the wall 200 via the block 202. Cooling of the heatsink 206 is generally greatly enhanced by positioning the powerconverter 120 in a location where cooler air can circulate and moveacross the radiator fins of the heat sink 206.

The power converter 120 of FIG. 2 is provided as one example a devicethat can be used to convert thermal energy to electrical energy to powerthe combustion controller 132. However, any type of converter that iscapable of producing sufficient power without interfering with theprimary function of the combustion reaction 116 can be used.

FIG. 3 is a simplified diagram showing a combustion system 300 accordingto another embodiment. The combustion system 300 differs from thecombustion system 100 of FIG. 1 primarily in the structure and operationof the switch module 302, which will be described below. Because theremaining elements are substantially similar to corresponding elementsdescribed with reference to FIG. 1, they will not be described in detailhere.

The switch module 302 includes a first switch 304 configured to controla source of power for the combustion controller 132, and a second switch306 configured to control a source of power for charging the powerstorage module 134. The first switch 304 is a SPDT-type switch with acommon node electrically coupled to the input terminal of the combustioncontroller 132, a first position switch node electrically coupled to thepower converter 120, and a second position switch node electricallycoupled to the power storage module 134. The second switch 306 is aSPTT-type switch with a common node electrically coupled to the powerstorage module 134, a first position switch node electrically coupled tothe external power supply 150, a second position switch nodeelectrically coupled to the power converter 120, and an off position.The first and second switches 304, 306 are configured so that while thesecond switch is in its first position, the first switch cannot move toits second position.

The switch module 302 is functionally very similar to the switch module138 of FIG. 1, in that it is controlled by the control module 136 toselect the source of power for the combustion controller 132 on thebasis of the output level of the power converter 120 and the SOC of thepower storage module 134. However, one significant difference is thatthe switch module 302 effectively isolates the combustion controller 132from any direct electrical connection with the external power supply150. Thus, even in the event of a malfunction, the danger of highvoltage being transmitted from the combustion controller 132 to anothersubsystem is significantly reduced.

See U.S. patent application Ser. No. 61/806,357, referenced above, for amore detailed disclosure related to high-voltage isolation.

In the embodiments of FIGS. 1 and 3, the respective switch modules areeach shown as including a pair of mechanical switches 140, 142, and 304,306. These examples are provided to illustrate some of the manyappropriate switching arrangements that can be used to perform thedisclosed functions. However, it is well understood in the art that manydifferent combinations of switches can be arranged in configurationsthat are functionally identical. Furthermore, other types of switchesare well known in the art, in addition to mechanical switches, includingsemiconductor-based switches and optical switches, etc. Accordingly, theclaims are not limited by the types or configurations of switchesdisclosed herein.

FIG. 4 is a flow chart illustrating elements of a method 400 foroperating a combustion system, according to an embodiment. For thepurposes of the present disclosure, the method 400 will be describedwith reference to the combustion system of FIG. 1. The first stepfollowing the start of the process at step 402 is the initiation of thecombustion reaction at step 404. At step 406, the output of the powerconverter is compared to a first power threshold value. If the outputdoes not exceed the first power threshold (NO path), the combustioncontroller is powered by energy from the power storage module (step408), and the process returns to step 406 to repeat the comparison.Typically, when the burner assembly is first ignited, the powerconverter will not immediately generate much power as the system beginsto heat up. Thus, the process cycles through steps 406 and 408 until, asthe heat received by the power converter increases, the output risesabove the first power threshold.

If the comparison at step 406 shows that the output of the powerconverter exceeds the first power threshold, the process proceeds tostep 410, in which the control module controls the switch module todecouple the power storage module from the combustion control module,and in its place, couple the power converter to the combustion controlmodule. The process then moves to step 412, in which the output of thepower converter is compared to a higher, second power threshold value.If the output does not exceed the second power threshold, the processreturns to the first comparison step at 406, and cycles through steps406-412 until the output rises above the second power threshold (ordrops below the first threshold). Of course, once the switch module hasbeen moved to a particular switch configuration, such as in the firstiteration of step 410, it is not necessary to change the configurationwhen that same step is repeated during a repeating cycle of steps.

If the output of the power converter exceeds the second power thresholdat step 412, the process proceeds to step 414, in which thestate-of-charge (SOC), i.e., the available stored energy in the powerstorage module is compared to a storage threshold to determine whetherthe power storage module is fully charged. If the available storedenergy exceeds the storage threshold, the process again returns to step406, and cycles through steps 406-414 until some condition changes.

Typically, immediately following a start up of the combustion system,the power storage module will have been drawn down, somewhat, inasmuchas power for operating the combustion control module was drawn therefromwhile the system initially warmed. If the available stored energy doesnot exceed the storage threshold, the process proceeds to step 416, inwhich the control module controls the switch module to couple the powerconverter to the power storage module for charging—without decouplingthe power converter from the combustion control module. In thisconfiguration, the power converter provides power to operate thecombustion control module while simultaneously charging the powerstorage module.

From step 416, the process returns to the first comparison step at 406and cycles through steps 406-416 until the power storage module is fullycharged. When the power storage module is charged to the point that theavailable stored energy exceeds the storage threshold at step 414, thecontrol module controls the switch module to decouple the powerconverter from the power storage module, and the process again returnsto step 406 and repeatedly cycles through steps 406-414.

FIG. 5 is a flow chart illustrating elements of a method of operation500 according to another embodiment. The method 500 is similar in mostrespects to the method 400 of FIG. 4, except that it is directed tooperation of a combustion system that includes a connection to anexternal power supply, such as, for example, the systems of FIGS. 1 and3. Only the process steps that are new, relative to the steps describedwith reference to FIG. 4, will be described in detail. Those that aresubstantially similar to the steps of FIG. 4, and bear the samereference numbers, will not be described again.

In the process 500, if the comparison at step 406 shows that the outputof the power converter does not exceed the first power threshold, theprocess proceeds to step 507, in which the available stored energy inthe power storage module is compared to a first storage threshold. Thefirst storage threshold corresponds to a minimum level of stored energythat is considered to be sufficient to reliably power the combustioncontrol module. If the available stored energy exceeds the first storagethreshold, the process proceeds to step 408. If not, the processproceeds to step 509, in which the control module controls the switchmodule to couple the external power supply with the combustion controlmodule. The process then returns to step 406, and cycles through steps406-509 until some condition changes.

At step 414, the available stored energy in the power storage module iscompared to a second storage threshold. The second storage thresholdcorresponds to the storage threshold described with reference to step414 of FIG. 4, and corresponds to a fully charged condition of the powerstorage module. If the available stored energy does not exceed thesecond storage threshold, the process proceeds to step 416, aspreviously described. If the available stored energy does exceed thesecond storage threshold, the process proceeds to step 517, the controlmodule controls the switch module to decouple the power storage modulefrom the power storage module and to couple the power converter to theexternal power supply. Surplus power is thus transmitted from the powerconverter to the external power supply, where it may be used to chargeexternal power storage units, to offset power draw from a municipalgrid, etc.

Various embodiments are described in modular form, i.e., as including anumber of modules, each having a specific function, such as, a controlmodule, a switch module, etc. This is done in order to provide a clearand simple description of the disclosed embodiments. However, accordingto various embodiments, the functions of two or more modules can beperformed by a single structure, the functions of a module can bedistributed among a number of modules, or some or all of the modules canbe integrated so as to be inseparably combined. Furthermore, it is notessential that all the disclosed components of a system be collectedtogether in a single enclosure or unit. Instead, elements may be locatedsome distance apart. Claims that recite a number of modules configuredto perform specific functions are not limited to structures in whichcorresponding modules can be separately identified. Instead, such claimsread also on devices that are configured to perform the functions ofeach of the recited modules, without regard for the physical arrangementof the devices or whether the devices include individual modulescorresponding to the recited modules.

Ordinal numbers, e.g., first, second, third, etc., are used in theclaims according to conventional claim practice, i.e., for the purposeof clearly distinguishing between claimed elements or features thereof.The use of such numbers does not suggest any other relationship, e.g.,order of operation or relative position of such elements. Furthermore,ordinal numbers used in the claims have no specific correspondence tothose used in the specification to refer to elements of disclosedembodiments on which those claims read, nor to numbers used in unrelatedclaims to designate similar elements or features.

The abstract of the present disclosure is provided as a brief outline ofsome of the principles of the invention according to one embodiment, andis not intended as a complete or definitive description of anyembodiment thereof, nor should it be relied upon to define terms used inthe specification or claims. The abstract does not limit the scope ofthe claims.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the following claims.

What is claimed is:
 1. A system, comprising: a switch module; acombustion control module having a power input terminal operativelycoupled to the switch module and configured to control an electricalcharge applied to a combustion reaction of a burner assembly; a powerconverter having a power output terminal operatively coupled to theswitch module and configured to convert thermal energy to electricalenergy; a power storage module operatively coupled to the switch moduleand configured to store electrical energy; and a switch control moduleoperatively coupled to the switch module and configured to: monitor apower output level of the power converter, monitor a state-of-chargelevel of the power storage module, control the switch module toelectrically couple the power output terminal of the power converterwith the power input terminal of the combustion control module while thepower output level of the power converter is above a first powerthreshold, control the switch module to electrically couple the powerstorage module to the power input terminal of the combustion controlmodule while the power output level of the power converter is below thefirst power threshold, and control the switch module to electricallycouple the power output terminal of the power converter to the powerinput terminal of the combustion control module and to the power storagemodule while the power output level of the power converter is above asecond power threshold, higher than the first power threshold, and thestate-of-charge level of the power storage module is below a firststorage threshold.
 2. The system of claim 1, wherein the first powerthreshold corresponds to a minimum power level for powering thecombustion control module.
 3. The system of claim 1, wherein: the switchmodule includes an input terminal configured to be coupled to anexternal power source; and the switch control module is configured tocontrol the switch module to electrically couple the input terminal ofthe switch module to the power input terminal of the combustion controlmodule while the power output level of the power converter is below thefirst power threshold and the state-of-charge level of the power storagemodule is below a second storage threshold.
 4. The system of claim 3,wherein the second storage threshold is lower than the first storagethreshold.
 5. The system of claim 3, wherein the switch control moduleis configured to control the switch module to electrically couple thepower output terminal of the power converter to the power input terminalof the combustion control module and to the input terminal of the switchmodule while the power output level of the power converter is above thesecond power threshold and the state-of-charge level of the powerstorage module is above the first storage threshold.
 6. The system ofclaim 5, wherein the first storage threshold corresponds to a fullycharged condition of the power storage module.
 7. The system of claim 3,wherein the input terminal of the switch module is configured to receivepower from a local area power grid.
 8. The system of claim 1, whereinthe power converter is positioned to receive thermal energy from thecombustion reaction.
 9. The system of claim 1, wherein the powerconverter includes a thermoelectric element.
 10. A method, comprising:receiving thermal energy from a combustion reaction and converting aportion of the received thermal energy to electrical energy; if a levelof the converted electrical energy is above a first threshold, applyinga first portion of the converted electrical energy to the combustionreaction; if the level of the converted electrical energy is above asecond threshold, greater than the first threshold, and if an amount ofstored electrical energy in a storage device is below a first storagethreshold, increasing the amount of stored electrical energy in thestorage device by applying a second portion of the converted electricalenergy to the storage device; and if the level of the convertedelectrical energy is below the first threshold, applying a portion ofthe stored electrical energy to the combustion reaction.
 11. The methodof claim 10, comprising, if the level of the converted electrical energyis below the first threshold and the amount of stored electrical energyin the storage device is below a second storage threshold, lower thanthe first storage threshold, applying electrical energy from an externalpower source to the combustion reaction.
 12. The method of claim 11,comprising, if the level of the converted electrical energy is above thesecond threshold and if the amount of stored electrical energy in thestorage device is above the first storage threshold, applying the secondportion of the converted electrical energy to the external power source.13. A method, comprising: receiving thermal energy from a combustionreaction; converting the received thermal energy to locally generatedelectrical energy; detecting a level of the locally generated electricalenergy; if the detected level of the locally generated electrical energyis below a first threshold, applying, to the combustion reaction, storedelectrical energy from an energy storage device; and if the detectedlevel of the locally generated electrical energy is above the firstthreshold, applying only locally generated electrical energy to thecombustion reaction.
 14. The method of claim 13, comprising detecting astate-of-charge of the energy storage device, and wherein, if thedetected state-of-charge of the energy storage device is below a firststorage threshold and the detected level of the locally generatedelectrical energy is above a second threshold, greater than the firstthreshold, applying only locally generated electrical energy to thecombustion reaction, and storing a portion of the locally generatedelectrical energy as stored electrical energy.
 15. The method of claim14, comprising, if the detected level of the locally generatedelectrical energy is below the first threshold and the detectedstate-of-charge of the energy storage device is below the first storagethreshold, applying, to the combustion reaction, electrical energy froman external energy source.
 16. The method of claim 15, wherein theapplying electrical energy from an external energy source comprisesapplying electrical energy from a municipal power grid.
 17. The methodof claim 15, wherein applying electrical energy from an external energysource comprises applying electrical energy from a remotely-locatedenergy storage device.
 18. The method of claim 15, comprising, if thedetected level of the locally generated electrical energy is above thesecond threshold and the detected state-of-charge of the energy storagedevice is above a second storage threshold, greater than the firststorage threshold, transmitting a portion of the locally generatedelectrical energy to the external energy source.
 19. The method of claim13, wherein the detecting a level of the locally generated electricalenergy comprises comparing a potential at an output of a power converterwith a reference potential.